1. Field of the Invention
The field of invention relates in general to methods and apparatus for making snow, and, in particular, to methods and apparatus for maintaining ski slope snow quality in indoor skiing facilities.
2.Description of the Prior Art
It has been generally known that indoor ski slopes are covered with artificial snow in an enclosed area cooled to below 0.degree. C. in order to maintain the snow quality. In order to maintain an indoor slope at below 0.degree. C., it must be insulated from various sources of heat, such as exterior walls; the ground underlying the slope; latent and sensible heat of water droplets and indoor water vapor; generated and radiated heat of indoor machinery; and heat generated by skiers and ski slope personnel. These sources of unwanted heat must be dealt with by adequate air conditioning.
With adequate air conditioning equipment, artificial snow on the surfaces of skiing runway slopes ordinarily does not melt from heat derived from the ambient atmosphere, since the atmosphere is maintained at a freezing temperature. However, the snow quality does change due to the sintering of snow crystals caused by the pressure and friction applied to the surface of the snow by the weight of the skiers. Radiation heat from illumination will also change the quality of the snow.
The snow on a ski slope comprises a base of unfused, unpacked snow, which could be 30 cm or more in depth, and a thin packed surface crust about 1 cm thick. It is the condition of the crust that provides the "feel" of the slope sensed by skiers through their skis. Even though an indoor ski slope is fully air conditioned to a temperature below 0.degree. C., the quality of the top crust will eventually deteriorate by the wear imposed on the snow by the skiers. The unfused snow base beneath the crust, on the other hand, will deteriorate from invasion of heat from the ground underlying the ski slope. Accordingly, there has been a felt need for means to condition both the crust and the base of artificial snow to prolong its useful life and to reconstitute the snow after it has deteriorated beyond use.